Method and apparatus for recording and reproducing



gw. w. ROBERTS 2,292,014

METHOD AND APPARATUS FOR RECORDING AND REPRODUCING Filed July 7. 1939 s sheds-sheet 1 INVENTOR WILLIAM w. R BERTS Y Minn 4m ATTORNEY S W. W. ROBERTS Aug. 4, 1942.

METHOD AND APPARATUS FOR RECORDING AND REPRODUCING Filed July '7, 1959 3 Sheets-Sheet 2 7 4 A 2 W m I A 5 0 O 37 274 7 I 7 I INVENTOR WILLIAM B 7 W l RNEYS W. ROBERTS ATT I 4, 1942' w. w. ROBERTS 2,292,014

METHOD AND APPARATUS FOR RECORDING AND REPRODUCING Filed July '7, 1939 3 Sheets-Sheet 3 to balanced mod (afar c I I I A} I 1 1 j U EU l] mu mm B I] l9 INVENTOR 7 WILLIAM W. ROBERTS Patented Aug. 4, 1942 UNITED STATES PATENT O F C METHOD AND APPARATUS FOR, RECORDING AND REPRODUCING WilIiam W. Roberts, Trenton, J., assignor to Wireless Research Corporation,

Princeton,

N. J a corporation of New Jersey Application July 7, 1939, Serial No. 283,220-

44 Claims. (01. 179 -10053) The invention relates to both a method and apparatus or combination of devices particularly designed to record and reproduce, with high recording and reproducing, with high fidelity, the

entire audible frequency range. The invention necessarily also includes a method and apparatus for recording, with high fidelity, an increased range of frequencies or the complete audiblerange, and also a method and apparatus for reproducing, with high'fidelity, the recordings referred to above.

It is an object of the invention to devise a new and novel method of recording and reproducing, with high fidelity, a wide range of frequencies, such as sound waves and electrical oscillations.

Another object of the invention is. to construct a new and novel combination of devices for recording and reproducing, with high fidelity, the audible sound range.

A still furtherobject ofthe invention is to devise a new and novel method for recording a wide range of frequencies, such as electrical os-- cillations and the audible sound range, so that the range of frequencies may be reproduced with high fidelity.

Another object is to construct a new and novel combination of devices which are able. to record a de range of frequencies, such as the entire au ble sound range,, in such a fashionthat the reproduction thereof has high fidelity.

Another object is to devise a method of reproducing a recording of a wide range of frequencies, such as sound, which recording has been made in accordance with the recording invention herein.

A further. object is to construct a new and novel combination of devices for reproducing, with high fidelity, the recordings made in-accordance with the invention herein.

Another object is to devise a method and coinbination of devices for-reproducing the plurality of frequency bands which have been recorded,

as set forth above, by transforming the-recording or sound track of each-high frequency band into electrical oscillations, and each frequency band which has been converted into low freeduced assound waves. Another object is to devise a method and comquencies is then reconverted to its initial frequency band. Thereafter, all frequency bands are mixed or combined to reproduce the original range of electrical frequencies which is reprobination of devices for the recording'and reproducing of the entire audible range of sound as set forth in the two next preceding paragraphs. A still further object is to devise a new and novel sound-track such as for moving picture Other objects-of the invention will be more apparent from the following description taken in connection with the accompanying drawings,

illustrating preferred embodiments of the invention, in which:

showing a combination of devices, or the,electrical circuit by whicha wide range of frequencies, such, as the entire or a substantial part of the audible range of sound waves, is recorded in accordance with the invention. 7

Figure 2 is a view, partially diagrammatic, showing the combination of devices or the elec-' trical circuit by'which a recording of a wide range of frequencies, obtained by the circuit shown in Figure 1, may be reproduced.

Figure 3 is a view, partially diagrammatic, of another electrical circuit or combinationbf devices for recording a wide range of frequencies, such as the entire or substantially the entire audible range of sound frequencies, utilizing the same method'used by the circuit of Figure 1 to accomplish this result.

Figure 4 is a diagrammatic view of another electrical circuit or combination of. devices by which a recording made in accordance with the inventionherein can be reproduced with high fidelity.

Figure 5 shows means for producing a carrier.

frequency for modulating the high frequency band or bands inthe recording of a wide range I of frequencies, such as the entire or a substantial part of the audible range of sound frequencies,

and also for demodulating the high-frequency band or bands in reproducing a recording in ac 55 cordance with the invention.

modulating and demodulating the band or hands of frequencies and particularly the high frequency band or bands.

Figure 7 shows a portion of a moving picture film on which a recording of a plurality of tracks is made inaccordance with the invention herein.

Present-day apparatus and methods of recording and reproducing sound, such for example as is commonly .used with talking moving pictures, are incapable of accurately recording and reproducing frequencies in excess of 7500 to 8000 'cyclesper second. At higher frequencies numerous factors are introduced with present methods which tend to reduce high frequency responsasome of which factors are inter-electrode capacitance, capacitance shunting of connecting circuits between photocell and amplifier, and the inherent inertia of gas cells at higher frequencies. Also when the light scanning slit is reduced to very small proportions, as is necessary in order to reproduce the very high frequencies, the amount of light which reaches the photocell is unbelievably small, so that the output of the photocellis well below the threshold of ground noise of the amplifiers. high frequencies therefore becomes impossible because the tube noise of the amplifier stage or stages is also amplified and drowns out the high frequency sound Waves or renders their reproduction unsatisfactory.

. Again, at the higher audible frequencies and particularly the frequencies in the neighborhood of 5,000 cycles per second, and higher, the recording of each wave upon the recording track approaches in dimension the size of the grain structure of the film which also tends to distort the wave shape. Also the wave forms of the recording at these high frequencies in the audible range are invariably so fine or close that they are lost through printing and developing processes. If the recording of higher frequencies were attempted on recording disks, the above dilficulties would be multiplied because of the larger grain structure of disk material, as compared with the grain structure of a film. The

- inability of present Systems to reproduce or reproduce accurately the upper harmonics of musical instruments is the one factor, more than any other, that makes present motion picture sound systems unpleasant to listen to particularly at higher volumes. The inaccurate reproduction of upper harmonics produces a metallic or a tinny overtone in music and other sounds. Both the loss of upperharmonics and their inaccurate reproduction is caused by electrical and optical deficiencies in the present-day systems.

It is to be understood that the invention to be described herein, although particularly applicable to the recording and reproduction of sound frequencies, is applicable to any frequencies and to practically any range'of frequencies, because by selecting the proper modulating or carrier frequency, the high frequencies can be converted to low frequencies in the range from to 8000 cycles which present-day equipment can record and reproduce with high fidelity. Also the invention canbe practiced in a range of frequencies not exceeding 8000 cycles, al-

though within' this range the usefulness of theinvention is not as apparent since.present-day equipment works "satisfactorily'in this range.

In the form of construction illustrated in Figures '1 and 2, the audible range of the sound Amplification of these waves, or a desired part thereof, is transformed into electrical oscillations by any known means, such as a microphone l0, and amplified in any known manner, such as by the means A.dia-

' grammatically illustrated. For the purpose of an example, a range of frequencies selected for recording and reproduction. by the method of the invention will be from 0 to 15,000 cycles per second, which range is about twice that now satisfactorily recorded and reproduced and is substantially the full audible range. It isundenstood that the invention isapplicable to a lesser or greater frequency range.

The circuit H from the microphone is divided into a plurality of branch circuits, such as .the circuits l2 and i3. One of these branch circuits, namely the circuit 52, has a wave filter or filtering means l6 which passes or selects a low band of frequencies, which in moving picture recording work may range from 0 to 8000 cycles, and suppresses all other frequencies. This band of low frequencies may then be recorded by any suitable means i? such as upon a sound track ill of a moving picture film E9 of Fig. 7. This manner of recording is known to the art. The second branch circuit I3 has a filtering means 29 which passes a band of frequencies, for example, from 8000 to 15,000 cycles, and suppresses the low frequencies.

It is evident that the range of sound waves or frequencies from 0 to 15,000 cycles has been transformed into corresponding electrical oscillations which have been divided or separated into a plurality of frequency bands, two being particularly described. The filters or filtering means it and 20, which are used to divide or separate the entire frequency range into branches or separate frequency bands, may be of any suitable kind which have a sharp cut-off frequency curve. Th high frequency band is transmitted through a matching transformer Hi to means which converts the frequencies of this band into low frequencies capable of being recorded by known systems upon a sound track, such as the sound track of a moving picture film.

The high frequency band is converted to a low frequency by modulating the same with a carrier frequency of, say, 7500 cycles to produce a low frequency side band and a highv frequency side band in a known manner. This low frequency side band, in the illustrated range of 8000 to 15,000 cycles for the high frequency band, includes frequencies from 500 to 7500 cycles. The high frequency side band and the carrier frequency are suppressed and the low frequency side band is recorded to form a recording or track, such as the sound track 2i upon the film I9 of Figure 7., This low frequency side band can be recorded in the same manner and with the same kind of equipment which was used to record the low frequency band since its range of frequencies is well within the range capable of being recorded by present-day systems.

The modulation or conversion of the high frequency band is accomplished by providing an oscillator 22 which preferably develops a fundamental frequency of, say, 1500 cycles. cycles pass through a harmonic producer 23,

and the filter 24 selects, for example, the fifth harmonicof 7500 cycles which is the carrier.fre-

quency'and is impressed upon the amplifier clr- .cuit 25 through the transformer 26. The carrier frequency may be directly produced if desired, however there are certain advantages in v the method described such as greater ease and The 1500 accuracy in recording a lower carrier frequency. The amplified carrier frequency preferably passes through a balanced H pad-21 which is connected with the input of the modulating means 30. The modulatingmeans particularly illustrated is a Hartley balanced type of modulator, such a that described in Patent 1,419,562, which produces a low frequency side band and a high frequency side band and suppresses or balances out the carrier frequency and the modulating frequency. A filter means ll passes the low frequency side band and suppresse the high frequency side band,. and the" low side band is recorded by recording means 32 in any suitable fashion to provide a second sound track, such as the second sound track 2| upon the moving picture film l9. The balanced modulator 80 and filter means 3| provide means for passing the low frequency side band and suppressing the modulating frequency, the carrier frequency and the high frequency side band. Other means may be used to accomplish this result.

The 1500 cycle fundamental or basic frequency may be. recorded by any suitable means 35 upon a third sound track 36 carried by the moving picture film 19. It is not essential to have this fundamental or basic frequency recorded, although it is beneficial to do so. because any shift or drift in the frequency has its effect upon the modulation of the higher frequency band or bands, and upon demodulation of these higher frequency bands, it is desirable that the same frequency shift occur and at the same time for more accurate reproduction of the sound frequencies. Itis to be understood, however, that satisfactory ,high fidelity. reproduction is. obtained even though the carrier frequency or a fundamental frequency is independently produced. In other words, it is not essential that the carrier frequency or a fundamental frequency be recorded and that a reproduction of this recording be used to demodulate the reproduction of the sound track of the low frequency side band which is a conversion of the high frequency band.

The recorded sound waves are reproduced in a manner and with to be described. frequency band a combination of devices now The,recording ll of the low is picked up and transformed into electrical oscillations by anysuitable reproducing means 38 which is diagrammatically illustrated. The recording 2| of the low frequency side band, that band, is picked up and transformed into electrical oscillations by any suitable reproducing means and amplified, all of which is accomplished by means indicatedgenerally at 35.

The recorded 1500 cycle frequency is picked up and transformed into electrical oscillations by the reproducing means 40, which oscillations may be amplified and then pass to the harmonic producer 4|. The harmonic producer creates or derives the harmonics of the 1500 cycle, and the filter 42 passes the fifth harmonic or a frequency. of 7500 cycles, and suppresses all other harmonies. Thi fifth harmonic is the carrier or demodulating frequency and has any drift or variation which occurred in the original modulating frequency. Any suitable harmonic producer is contemplated. If thereproducing circult or means is near or adjacent the recording circuit or means, the carrier producing circuit 22, 23,14, 25, 20 and 21 for the latter circult may be used, but if these two circuits are widely separated, as would be the case in the 3 moving picture field, then a separate means, as

described, must be provided for producing another carrier frequency for demodulation.

The 7500 cycle carrier frequency is amplified by r the circuit II and then passes through a balanced H pad 44, after which this carrier frequency is applied to the circuit carrying the-500 to 7500 cycles of the low frequency side band,

or the converted high frequency band. In other words, the carrier frequency is applied to the input of a demodulator means 45 which again may be of the Hartley balanced type, as previously mentioned, whereby the carrier frequency and the modulating oscillations are suppressed or balanced out. The demodulated oscillations produce a high and a low frequency side band. the latter being the initial frequency band of 8000 to 15,000 cycles. The output of the demodulator means is connected with a filter 46 which suppresses the low frequency side band and passes the high frequency side band which is the initial or original band of frequencies in the high frequency band. The balanced demodulator and filtering means comprise means for creating a high frequency side band and suppressing the carrier frequency, the modulating oscillations and the low frequency side band.

The reconverted band of frequencies is combined or mixed with the frequencies of thelow frequency or unmodulated band, whereby the complete initial range of electrical oscillations from 0 to 15,000 is reproduced. If these electrical oscillations are transformed sound waves,

then they may be connected to a loud speaker or other sound reproducer original range of sound waves.

Another apparatus or combination of devices is illustrated in Figures 3 and 4 for recording and reproducing a wide range of frequencies, such as sound waves, by the same method described in connection 'with the combination illustrated in Figures 1 and 2, but instead of using a. balanced modulator and demodulator of the Hartley type, these views illustrate a combination of devices .gutilizing; a Carson type of balanced modulator and balanced demodulator described in his Patent 1,343,306 which suppresses or balances out the is of the converted high frequency f l8 of a moving picture modulating oscillations but not the carrier frequency. The Carson balanced modulator and balanced demodulator difl'ers from-.the Hartley circuit in this respect.

The recording system shown in Figure 3 is substantially the same as that shown in Figure 1 with the substitution referred to above. The Pa ts. or devices which are the same have been given the same reference numerals, and hence need not be described in detail. Briefly, the microphone It transforms the sound waves into electrical oscillations which are then divided or separated by a plurality of branch circuits, two being particularly shown. Filter 15 passes alow frequency band and suppresses all other frequencies. The low frequency band is recorded by a recording means H, such as upon a sound-track film.

The filter 20 passes a high frequency band and suppresses all other frequencies, which high frequency band passes to the Carson type of balanced modulator 52. The Carson type of modulator functions in the manner described in his patent referred to above. In other words, by modulating with a carrier frequency of, say, 7600 cycles, there is produced a low frequency side band of to 7400 cycles, and a high frequency side band with the modulating oscillations suppressed or hal- 41 to reproduce the &

quency side band which is recorded upon a second sound track, such as the track 2| upon the moving picture film is. The high frequency side band and carrier is suppressed by the filter means.

It is to be understood that amplifiers A may be supplied any place where desired or needed in Jthe circuit with respect to thecircuit or combination shown in Figures 3 and 4, as well as that shown in Figures 1 and 2. The circuit illustrated in Figures 3 and 4 does not show an H pad in the carrier frequency circuit, such as the pad 21 and M shown in Figures 1 and 2. Such pads or equivalent means may be used if desired.

In the form of circuit illustrated in Figure 3, the carrier or demodulating frequency is shown as being 7600 cycles which may be produced in any known manner. The production of this frequency is illustrated in a general way by the oscillator means 53 which may producethe carrier frequency of 7600 cycles directly, or it may be produced by creating a basic or fundamental frequency, passing the same through an harmonic producer, and then with' suitable filter means pass the desired harmonic of 7600 cycles and suppress all other harmonics. This method was described in connection with the circuit of Figure 1. The carrier frequency, or a fundamental frequency from which a harmonic frequency of 7600 cycles may be derived, may be recorded such as upon a sound track 36 of the moving picture film 19 and the demodulating carrier frequency obtained therefrom.

The reproducingcircuit, illustrated in Figure 4, and its, method of operation are also much like the combination of devices shown in Figure 2,

' excepting that it uses a Carson type balanced demodulator, instead of a Hartley type, and. the identical parts have been assigned the same nu- .merical designation.

In reproducing the plurality of frequency bands into which the original frequency range has been divided, the recorded low frequency band is transformed into electrical oscillations in the same manner as described in connection with the construction and method of Figure 2. The recording 2! of the converted high frequency band is transformed into electrical oscillations which are demodulated by the Carson type of demodulator 56 utilizing a carrier frequency of 7600 cycles which corresponds with the carrier frequency used nected so that the electrical frequencies are then mixed or combined to reproduce the original 7 range of frequencies which may be amplified if g If the original range of frequencies desired.

were sound waves, then the reproduced electrical oscillations may be fed to a loud speaker 41 where the full range of from 0 to 51000 cycles of audible sound is reproducedwith accuracy or high quency band by this drift is corrected for; in

other words, the reproduction of the original modulating or carrier frequency automatically compensates for this drift in the original carrier wave. 7

Another method of producing the carrier frequency is illustrated inv Figure 5. The sound sprocket 60 of a moving picture camera and also of a moving picture projector runs at a speed which is substantially constant and its percentage of variation is very low. In other words, its uniformity of rotation is very high; An oscillation generator 6! is illustrated in Figure 5 as being connected to or carried upon thesound sprocket 60. This generator may produce the carrier frequency directly, or may produce. a fundamental or basic frequency which passes through a harmonic producer and the carrier frequency is derived therefrom, as previously described. The type of oscillation generator particularly illustrated in Figure 5 is described in the Horton Patent 1,799,795. It is to be understood that this oscillation generator connected to the sound sprocket of the moving picture camera generates the carrier frequency for modulating the high frequency sound band.

The same type-of oscillation generator, or an oscillation generator of any suitable kind, may be connected to the sound sprocket of the moving picture projector for: developing the carrier frequency-either directly or by generating a basic or fundamental frequency which passes through a harmonic producer, as previously described, from which the carrier frequency is derived. The carrier frequency is used in connection with the moving picture reproduction to demodulate the converted high frequency band whereby itsorlginal range of frequencies is;restored or reproduced.

Figure 6 illustrates another method of generating the carrier frequency, which generator is again connected'or coupled with the sound sprocket 65 of the moving picture camera and the same kind of carrier wave producer, or any other kind, maybe connectedwith the sound sprocket of the moving picture projector.

rier frequency or a basic or fundamental frequency from which the carrier frequency may be quency carried by the sound track. ,Since the In this construction, a transparent sleeve 66 may be directly carried upon the shaft 61. upon which the sound sprocket 65 is mounted. Upon this trans-.

. parent sleeve a -piece,of sound film is mounted which carries a sound track 68 of either the carsound sprocket 65 rotates at a very uniform speed, a very uniform carrier oscillation, or a basic or fundamental frequency from which the carrier is derived, is obtained. It should be noted, too, that any variations in the speed of the sound sprocket of the projector will create a slight drift in the frequency of the carrier wave and thereby tend to compensate-for the variations in speed of the sound sprocket in the sound reproduced from the sound track on the moving picture'fllm.

Preferably, the sound track 08 is a basic or fundamental frequency which passes through a harmonic producer 10 and a filter 19 selects the harmonic which is the desired carrier frequency. In this construction also amplifiers A may be provided wherever needed.

It has been described hereinbefore that the carrier frequency may be recorded or a fundamental frequency can be recorded from which the carrier frequency is produced. This fundamental frequency may be used to produce the carrier frequency for both the modulation or conversion of the high frequency band or bands into'a low frequency side band, and the demodulation of the low frequency side'band or bands by which the latter is reconverted into its initial high frequehcy band. It is to be understood, therefore, that a recording of a frequency from which the carrier frequency can be derived constitutes a definition of a recording, whether it be a recording of the carrier frequency, or a recordbefore.

.ing of .a fundamental frequency from which the carrier frequency may be produced.

Although the method and apparatus described herein have particular applicability to the previously described, which 2000 cycles pass to a harmonic producer and a prope selects the fourth harmonic, or 8000 cycles, both for modulating or converting the high frequency band of the two bands of sound frequencies into low frequencies and for demodulating the converted high frequency band to reproduce the original high frequency band.

It is also clear that by following the principles outlined above, it will be readily apparent that the invention is not limited to dividing the range of electrical frequencies, or the sound frequency range, into two branches or two bands of frequencies, but that it may be divided into a greater number of branches or frequencybands, thereby .lowering the frequency range in each branch-or frequency band for the full range of frequencies. In other words, if it is desired to record and reproduce a range from 0 to 183000 cycles, this initial range can be divided into three frequency bands of 6000 cycles each in three branch circuits. The low frequency band is recorded. Each high frequency band is modulated or converted to produce two low frequency side bands, and each low frequencyside band is recorded in the manner described herein- For reproduction of the original frequency range, the recordings are converted into electrical oscillations. Each low frequency side band is then demodulated with a carrier frequency to produce a low frequency and a high frequency side band, the former being suppressed and the latter being combined with the other demodulated side band and the unmodulated recording and,reproduction of sound waves, the

method and apparatus are applicable to record,

with high fidelity, a range of electrical oscillations carrying intelligence of any nature. The

range of frequencies which can be recorded and reproduce djwith high fidelity, by the method and combination of devices of the invention is considerably greater than the range which can be recorded and reproduced by practicing known methods and using known combinations of apparatus. The wide range of oscillations to be recorded and reproduced may be such oscilla-' tions like sound waves which must be transformed into electrical oscillations and then reproduced as' sound, or may be electrical oscillaitions which need not be transformed into some other kind of waves or oscillations. v

It will be observed that by the method of recording and reproducing sound as described, the

recorded frequencies are, not in excess of 8000 cycles which present-day apparatus is well capaor high fidelity. The ultimate reproduction, however, in the example illustrated, is throughout a range of from 0' to 15,000 cycles and a flat or substantially flat frequency response is obtained throughout this entire range.

Itis cleghat there may be many variations in the de ofrecording and reproducing a wide range of frequencies as described herein. For example, the recording range can be raised to 16,000 cycles by properly designing the filters and utilizing, say, an 8000 cycle carrier frequency or wave. The modulation of the 8000 to 16,000 frequency wouldresult in a low frequency side ble of recording and reproducing with accuracy band ranging from 0 to 8000 cycles which would than the 1500 cycles present-day equipment is capable of re frequency band to reproduce the initial frequency range. The electrical oscillations, if originally transformed from sound waves, may be reproduced as sound waves with a loud speaker. The

' carrier frequency or frequencies'is selected so that the plurality of. bands into which the full range of frequencies has been divided can be convertedinto a band of low frequencies which is well within'the range of frequencies which ording delity. fairly and reproducing with accuracy or high The filters or filter means used should be sharp and particularly the filters used to rate or divide the entire range of frequencies into separate frequency bands. The filters used after the modulators and demodulators need not be particularly sharp, although this may depend upon the spread between the low frequency and high frequency side bands.

This invention is presented to fill a need for improvements in -a method and apparatus for recording and reproducing. It is understood that various modifications in structure, as well as changes in mode of operation, assembly, and manner of use, may and often do occur to those skilled in the art, especially after benefiting from the teachings of an invention. Hence, it will be understood that this disclosure is illustrative .of

preferred means of embodying the invention in useful form by explaining theconstruction, operation and advantages thereof. What is claimed is:

1. A method of recording and reproducing a wide range of electrical frequencies oroscillations' comprising separating-the range of frequencies of the electrical V rality of frequency ban converting at least one of said frequency bands into a band of low frequencies by modulating the rier frequency, recording -each converted fre quency, band and any unconverted frequency i'ly designed mmsepaoscillations into a plusamewith a carquencies of the electrical oscillations into frequencies by trical oscillations,

' quencies into a band,

hand, transforming the recording of each frequen-cy hand into electrical oscillations, reconverting each converted frequency hand to its initial frequency range by demodulating with a carrier frequency the same as that of the rnodulating carrier frequency-for that frequencyband, and mixing the reconverted frequency band or hands with each other and with any unconverted frequency band or hands to restore the initial frequency range.

2 A method of recording and reproducing a wide range of electrical. frequencies or oscillations comprising separating the range of frea pluraiity of frequency bands, converting at least one of said frequency hands into a band of low frequencies by modulating the same with a carrier of a desired frequency, recording each con verted frequency band and any unconverted frequency hand, recording a frequency from which each carrier frequency can be derived, transforming the recording of each frequency band into electrical oscillations, transforming each frequency recording into the carrier frequency, reconverting each converted frequency band to its initial frequency range by demodulating with a carrier frequency the same as that of the modulating carrier frequency with which each converted frequency band was modulated, and mixing each reconverted frequency band with any other and any unconverted frequency band to restore the initial frequency range.

3. A method of recording and reproducing a wide range of. sound frequencies or waves comprising transforming the sound waves into electrical oscillations, separating the range of ,frequencies of the electrical oscillations into a plurality of frequency bands, converting at least one of said frequency hands into a band of low modulating the same with a carrier frequency, recording each converted frequency bands and any unconverted frequency band, transforming the recording of each frequency band into electrical oscillations, reconverting each; converted frequency band to its initial frequency range by demodulating with a carrier frequency the same as that of the modulating aeeaoic wide range of sound frequencies or waves cornprising transforming the sound waves into electrical oscillations, separating the range of freverting each higher band of frequencies into a band of low frequenciesby modulating with thecarrier frequency, recording each of said' converted frequency bands, recording a frequency from which the carrier frequency can be derived,

transforming the recording of each frequency i,

band into electrical oscillations, reproducing the carrier frequency from the recorded frequency, reconverting each higher frequency band to its initial frequency range by demodulating with the carrier frequency, mixing thereconvertedhigh frequency bands with each other and'with the low frequency band, and reproducing the oscillations of the wire frequency range as sound waves.

3. A method of recording and reproducing awide range of sound frequencies or waves comprising transforming the sound waves into electrical oscillations, separating the range of fre quencies of the electrical oscillations into a plurality of frequency bands, recording the low fre quency band, producing a fundamental frequency from which a carrier frequency may be derived, converting each higher hand of frequencies into a bandof low frequenciesby modulating with the carrier frequency, recording each of said converted frequency bands, recording the aforesaid I fundamental frequency, transforming the recordcarrier frequency with which that frequency band was modulated, mixing the reconverted band or hands with each other and with any unconverted frequency band or hands to restore the initial frequency range, and reproducing the oscillations of the wide frequency range as sound waves.

4. A. method of recording and reproducing a wide range of sound frequencies or waves comprising transforming the sound waves into elec-,

separating the range of frequencies of the electrical oscillations into'aplurality of frequency bands, recordingthe low frequency band, convertingeach higher band of fre-= of lowfrequencies by modulating with a carrier frequency, recording each of'said converted frequency bands, transforming the recording of each frequency band into electrical oscillations, reconverting each higher frequency band to its initial frequency range by demodulating with a carrier frequency the same ing of each frequency band into electrical oscillations, reproducing the carrier frequency from the recording of the fundamental frequency, re-

converting each higher frequency band to its,

initial frequency range by demodulating with the carrier frequency, mixing the reccnverted high frequency bands with each other and with the low frequency band, and reproducing-the electrical oscillationsof the wide frequency range as sound waves.

"I. A method of recording a wide range of electrical frequencies or oscillations comprising separating the range of frequencies of the electrical oscillations-into a plurality of frequency bands,

' converting at least one of saidfrequency bands into a band of low frequencies-by modulating the same with a carrier frequency, and recording each converted frequency band and any unconverted frequency band.

8. A method of recording a wide range of electrical frequencies or oscillations comprising separating the range of frequencies of the electrical oscillations into a plurality of frequency bands,

converting at least one of said frequency bands I into a band of low frequencies by'modulating the as'that of the modulating carrier frequency for that respective frequency band, mixing the reconvex-ted high frequency band or bands with each other and with the low frequency band, and reproducin'g'the oscillations of the wide frequency range as sound waves.

5 A method of recording a'nd reproducing a same with a carrier of a desired frequency, recording each converted frequency band and any unconverted frequency band, and recording a frequency from which each carrier frequency can be derived.

9. A method of recording a wide" range of sound frequencies or waves comprising transforming the sound waves into electrical oscillations, separating the range of frequencies ofthe electrical/ oscillations into a plurality of frequency bands, converting at least one of said frequency hands into a band of low frequencies by modulating the same with a carrier frequency,, and recording each converted frequency band and any unconverted frequency'band.

10'. A method of recording a wide range of sound frequencies compfisingtransforming the x ing ,the range of frequencies of the electrical oscillations into a plurality of frequency bands, recording the low frequency band, Producing a carrier frequency, converting each higher band of frequencies into a band of low frequencies by modulating with the carrier frequency, recording each of said converted frequency bands, and re-' cording a frequency from which a carrier frequency can be reproduced. Q

12. A method of recording a'wide range of sound frequencies comprising transforming the sound waves into electrical oscillations, separating the range of frequencies of the electrical oscillations into a plurality of frequency bands, recording the low frequency band, producing a fundamental frequency from which a carrier frequency may be derived, converting each. higher band of frequencies into a band of low frequencies by modulating with a carrier frequency, recording each of said converted frequency bands, and recording the aforesaid fundamental frequency.

13. A method of reproducing a wide range of electrical frequencies or-oscillations which have been separated into a plurality of frequency bands, at least one of said frequency bands having been converted into a band of low frequencies by modulating the same with a carrier frequency and each converted frequency band and any unconverted frequencyband having been recorded comprising transforming the. recording of each frequency band into electrical oscillations, reconverting each converted frequency band to its initial frequency range by demodulating with a carrier frequency the same as that of the modulating carrier frequency for that frequency band, and mixing the reconverted frequency band or bonds with each other and with any unconverted frequency band or bands to restore the initial frequency range;

14. A method of reproducing a wide range of electrical frequencies or oscillations which have been separated into a plurality of frequency bands, at least one of said, frequency bands having been converted into a band of low frequencies by modulating the same with a carrier of a desired frequency, and each converted frequency band and any unconverted frequency band and a frequency from which each carrier frequency canbe derived having been recorded comprising transforming the recording of each frequency band into electrical oscillations, transforming each frequency recording into the carrier frequency, reconverting each converted frequency band to its initial frequency range by demodulating with a carrier frequency the same as that of the modulating carrier frequency with which each converted frequency band was modulated, and mixing the reconverted frequency band or hands with each other and with any unconverted frequency band or hands to restore the initial frequency range.

15. A method of reproducing a wide range of sound frequencies or waves which have been separated into a plurality of frequency bands, at

least one of said frequency bands having been converted into a band of low frequencies by modulating the same with a carrier frequency, and each converted frequency band and any unconverted frequency band having been recorded comprising transforming the recording of each frequency band into electrical oscillations, reconverting each converted frequency band to its initial frequency range by demodulating with a carrier frequency the same as that of the modulating carrier frequency with which that fre quency band was modulated, mixing the reconverted band or bands with each other and with any unconverted frequency band or hands to restore the initial frequency range, and reproducing the oscillations of the wide frequency range as sound waves.

16. A method of reproducing a wide range of sound frequencies or waves which have been separated into aplurality of frequency bands, at least one of said frequency bands having .been converted into a band of'low frequencies by modulating with a carrier frequency and each of said frequency bands having been recorded'comprising transforming the recording of each frequency band into electrical oscillations, reconverting each higher frequency band to its initial frequency range by demodulating with' a frequency the same as that of the modulating carrier frequency for that frequency band, mixing the reconverted high frequency band or bands with each other and with the low frequency band, and reproducing the oscillations of the wide frequency range as sound waves.

17. A method of reproducing a wide range of sound frequencies which have been transformed into electrical oscillations, the electrical oscillations having been separated into a plurality of frequency bands, each higher band of frequencies having been converted. into a band of low frequencies by modulating with a carrier frequency, all of which bands having been recorded as well as a frequency from which a carrier frequency can be reproduced comprising transforming the recording of each frequency band into electrical oscillations, reproducing the carrier. frequency from the recorded frequency, reconverting each higher frequency band to its initial frequency range by demodulating with the carrier frequency, mixing the reconverted high frequency bands with each other and with the low frequency band, and reproducing the electrical oscillations of the wide frequency range as sound waves.

18. A method of reproducing a wide range of sound frequencies which have been transformed into electrical oscillations and the range of frequencies of the electrical oscillations have been separated into a plurality of frequency bands with each higher band of frequencies being converted into a band of low frequencies by modulating with a carrier frequency and each of said frequency bands and a fundamental frequency from which a carrier frequency can be derived having been recorded comprising transforming the recording of each frequency band into electrical oscillations, reproducing the carrier frequency from the recording of the fundamental frequency, reconverting each higher frequency band to its initial frequency range by demodulating with the carrier frequency, mixing the reconverted high frequency bands with each other and with the low frequency band, and reproducing the electrical oscillations of the wide frequency range as sound waves. I

19. An apparatus for recording and reproducing a wide range of electrical frequencies or oscillations carried by a circuit'comprising a plurality of branch circuits, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies whereby the initial range of frequencies is separated into a plurality of frequency bands, means producing a carrier frequency connected with at least one branch circuit for mcdulating the frequency band carried thereby into a low frequency and a high frequency side band, means in the output of each circuit carrying a modulated frequency band for passing the low frequency side band and suppressing the high frequency side band, the modulating oscillations and the carrier frequency, means for recording each low frequency side band and any unmodulated frequency band, means for v each recording for transforming the same into electrical oscillations, the carrier frequency producing means being connected with each of the next aforesaid means which carries a side band frequency for demodulating each side band freside band', means for passing the high frequency side band and suppressing the low frequency side band, the carrier frequency and the modulating frequency whereby the initial frequency band is quency into a low frequency and a high frequency 2 recreated, the output of each of the next aforesaid means and any transforming means carrying an unmodulated frequency band being connected whereby the demodulated frequency band or bands are mixed with each other and with any unmodulated frequency band or hands torestore the initial frequency range.

20. An apparatus for recording and reproducing a wide range of electrical frequencies or uscillations carriedby a circuit comprising a plrurality of branch circuits, filtering means in each 40,

branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies wherebythe initial range of frequencies is separated into a plurality of frequency bands, means producing a carrier frequency connected with at least one branch cir cuit for modulating the frequency band carried I thereby into a low'frequency and a high frequency side band, means in the output of each the low frequency side band and suppressing the high frequency side band, the carrier frequency and the modulating oscillations, means for recording each low frequency side band and any circuit carrying amodulated current for passing 5 unmodulated frequency band, means for each a low frequency side band for demodulating the same into a low frequency and a high frequency side band, means for passing the high frequency side band and suppressing the low frequency side band, the demodulating oscillations and the. car-' rier frequency whereby the initial frequency band is recreated, the output of each of 'the aforesaid means being connected and the transquency band whereby the demodulated frequency band or bands are mixed with each other and with any unmodulated frequency band or bands restore the initial frequency range.

ing -a wide range of electrical frequencies or oscillations carried by a circuitcomprising a plurality of branch circuits, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and sup-. pressing other frequencies whereby the-initial range of frequencies is separated into a plurality of frequency bands, means producing a carrier frequency connected with at least one branch circuit for modulating the frequency .band carried thereby into a low frequency and a high frequency side band, means in the output of each circuit carrying a modulated current for passing the low frequency side band and suppressing the high frequency side-band, the carrier-frequency and the modulating oscillations;

quency side band into a low frequency and ahigh' frequency side band, means for passing the high frequency side band and suppressing the low frequency side band, the demodulated side band and the carrier frequency whereby the initial frequency band is,recreated, the output of each of the aforesaid means and any transforming means carrying an unmodulated frequency band being connected whereby the reconverted frequency band or bands are mixed with each other and with *any unmodulated frequency band or bands to restore the initial frequency range.

22. An apparatus for recording and reproducing a wide range of; electrical frequencies or oscillations carried by; a circuit comprising a plurality of branch circuits, filtering means in each branch circuit for passing a .band of frequencies of the electrical oscillations and suppressing other frequencies whereby the initial range of frequencies is separated into a plurality of frequency bands, a balanced modulator connected quency side band, filter means in the output of each balanced modulator for passing. the low frequency side band and suppressing the high frequency side band, means for recording each low frequency side band and any unmodulated frequency band, means for each recording or transforming the same into electrical oscillations, a balanced demodulator connected with each of the next aforesaid means which carries a side band frequency, the carrier frequency producing means being connected withthe input side of each demodulator for demodulating each forming means carrying an unmodulated fre- 7 21. Aifapparatus for recording and reproduc- 7 side band frequency into alow vfrequency and a high frequency'side band, filter means for passing the high frequency side band and suppressing the. low frequency side band whereby the initial frequency band is recreated, and the output of each of the next aforesaid means and the output of all transforming means carrying an unmodulated frequency band being connected whereby the demodulated frequency band or bands are mixed with each other and with any ing the same unmodulated frequency band or bands to restore the initial frequency'range.

23. An apparatus for recording and reproducing a wide range of sound frequencies or waves comprising means to transform the waves into electrical oscillations, a plurality of branch circuits leading therefrom, filtering means in each branch circuit for passing a band of frequencies of the electrical-oscillations and suppressing other frequencies whereby the initial range of frequencies is separated into a'plurality of frequency bands, means producing a carrier frequency connected with the output side of the filter means passing a high frequency band for into a low frequency and a high frequency side band, means in the output of each circuit carrying a modulated frequencyband for passing the low frequency side band and suppressing the car rier frequency, the modulating oscillations and the high frequency side band, means for recording each low frequency side band and the unmodulated low frequency band in separate sound tracks, means for each recording for transforminto electrical oscillations, carrier frequency producing means connected with the output side of the transforming means which carlies a side band frequency for demodulating each side band frequency into a low frequency and a high frequency side band, means for passing the high frequency side band and suppressing the carrier frequency, the demodulating oscillations and low frequency side band whereby the initial frequency band or hands is recreated, the output of each of the next aforesaid means andof the transforming means for the low frequency band. being connected whereby the demodulated frequency band or bands are mixed with each other and with the unmodulated frequency band to restore the initial frequency range, and means toreproduce the initial frequency range as sound waves.

24. An apparatus for recording and reproducing a wide range of sound frequencies or waves comprising means to transform the sound waves into electrical oscillations, a plurality of branch circuits leading therefrom, filtering means in each branch circuit for passing a, band of frequencies of the electrical oscillations and suppressing other frequencies whereby 'the initial range of frequencies is separated into a plurality of frequency bands, means producinga carrier frequency connected with the output side of one filtering means for modulating the frequency band carried thereby into-a low frequency and a high frequency side band, means in later! frequency band for passing the low frequency side band and suppressing the carrier fre quency, the modulating frequency and the high frequency side band, means for recording each low frequency side band and the unmodulated frequency band in, separate sound tracks, means for each recording for transforming the same into electrical quency producing means connected with the output side of at least one of the next aforesaid means which carries a side band for demodulat ingthe side band into a low frequency and'a.

modulating. the same each circuit carrying a moduoscil1ations, a second carrier freelectrical oscillations, a

high frequency side band, means for passing the high frequency side band and suppressing the low frequency side band, the demodulating oscil lations and the carrier frequency whereby the initial frequency band each of the next aforesaid means and of any transforming means carrying-an unmodulated frequency band being connected whereby the deis recreated, the output of ,9 modulated frequency. band or bands are mixed with each other and with any unmodulated frequency band or bands quency range.

25. An apparatus for recording and reproducing a wide range of sound frequencies or waves comprising means to transform the waves into plurality of branch circuits leading therefrom, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies whereby the quencies is separated into a plurality of frequency bands, a balanced modulator connected with at least one of the-filter means carrying a higher frequency band, means producing a carrier frequency and connected with the input side ofeach balanced modulator for modulating the frequency band carried thereby into a low frequency and a high frequency side band, filter means in the output of each balanced modulator for passing the low frequency side band and suppressingthe high frequency side band, means for recording each low frequency side band and the unmodulated 'low frequency band and a frequency from which high frequency side band and suppressing the low frequency side band whereby the initial frequency band is recreated, the output of each of the next aforesaid means and the transforming means for the unmodulated frequency bandbeing connected whereby the demodulated frequency band or bands are. mixed with each other and with the unmodulated frequency band to restore the initial frequency range, and means to reproduce the initial frequency range as sound waves.

26. An apparatus for recording and reproducing a wide range of sound frequencies or waves comprising means to transform the waves into electrical oscillations, a plurality of branch circuits leading therefrom, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies whereby the initial range of frequencies is separated into a plurality of frequency hands, a balanced modulator connected with at least one of the filter means carrying a higher frequency band, means producing a fundamental frequency from which a carrier frequency can be derived and connected with the input side of each balanced modulator for modulating the frequency band carried thereby into-a low frequency and a high frequency side band, filter means in the output of each balanced modulator for passing the low frequency side band and suppressing the high frequency side band, means for recording each 'low' frequency side band and the unmodulated low frequency band and the fundamental frequency upon separate sound tracks, means for each recording for transforming the same into electrical oscillations, a balanced demodulator connected with each of the next aforesaid means which carries a side band frequency, means for producing a carrier frequency from the fundamental frequency sound track and connected with the input side of each to restore the initial fre-' initial range of frequency and a quency and unmodulated frequency band, and

oscillations and demodulator for demodulating each side band frequency into a low frequency anda high frequency side band, filter means for passing the high frequency side band and suppressing the low frequency side band whereby the initial frequency band is recreated, the output of each of the aforesaid means and the transforming means for, the unmodulated frequency band being connected whereby the demodulated frequency band or bands are mixed with each other and with the unmodulated frequency band to restore the initial frequency range, and means to reproduce the initial frequency range as sound waves.

27. An apparatus for recording a wide range of electrical frequencies or oscillations carried by a circuit comprising a plurality of branch cir- 1 and a' high frequency side band,.means in the output of each circuit which carries a modulated frequency band for passing the low frequency side band and suppressing the high-frequency side band and-the carrier frequency, and means for recording each low frequency side band and any unmodulated frequency band.

28. An apparatus for recording a wide. range of electrical frequencies or oscillations carried by a circuit comprisinga plurality of branch circuits, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies whereby the initial range of frequencies is sepa rated into a plurality of frequency bands, means producing a carrier frequency connected with at least one branch circuit for modulating the frequency band carried thereby into a low frehigh frequency side band, means in the output of each circuit carrying a modulated frequency band for passing the low frequency side band and suppressing the high frequency side band means for recording each low frequency side band and any unmodulated frequency band.

29. An apparatus for recording a wide range of electrical frequencies or oscillations carried by a circuit comprising a plurality of branch circuits; filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies whereby the initial range of frequencies is separated into a plurality of frequency bands, means producing a carrier frequency connected with at least one branch circuit for modulating the frequency band carried thereby into a low frea high frequency side band, means in the output of each circuit carrying a modulat 'ed frequency band for passing the low frequency side band and suppressing the high frequency side band and the carrier frequency, means for recording each low frequency side band and any means for recording a frequency from which the carrier fre quency can be derived.

30. An apparatus for recordings, wide range of electrical frequencies or oscillations carried by a circuit'comprising a pluralityof branch circuits, filtering means in each branch circuit for passing a band of frequencies of the electrical suppressing other frequencies and the carrier frequency, and v whereby the initial ran as of frequencies is separated into a plurality of. frequency bands, a balanced modulator connected with at least one of the filter means, means producing a carrier frequency connected with the input side of at least one balanced modulator for modulating the fre: quency band carried thereby into a low frequency and a high frequency side band, filter means in the output of each balanced modulator for passl ing the low frequency side band and suppressing the high frequency side band, 7 and means for recording each low frequency side band and any unmodulated frequency band.

31. An apparatus for recording a wide range of sound frequencies or waves comprising means to transform the waves into electrical oscillations, a plurality of branch circuits leading therefrom, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies whereby the initial range of frequencies is separated into a plurality of frequency bands, means producing a carrier frequency connected with the output side of the filter means passing a high frequency band for modulating the same into a low frequency and a high frequency side band, means in the output of each circuit carrying a modulated frequency band for passing the low frequency side band and suppressing the carrier frequency and the high frequency side band, and means for recording each low frequency side band and the unmodulated low frequency band in separate sound tracks.

32. An apparatus for recording a wide range of sound frequencies or waves comprising means to transform the sound waves into electrical oscillations, a plurality of branch circuits leading therefrom, filtering means in each branch circuit for passinga band of frequencies of the electrical oscillations and suppressing other frequencies whereby the initial range of frequencies is separated into a plurality of frequency bands, means producing a carrier frequency connected with the output side of one filtering means for modulat ing the frequency band carried thereby into a low frequency and a high frequency side band, means in each circuit carrying a modula'tedfrequency band for passing the lowfrequency side band and suppressing the carrier. frequency and the high'frequency side band,'and means for recording each low frequency side band and any unmodulated frequency band and a frequency from which a. carrier frequency can be derived in separate sound tracks.

33. An apparatus for recording a wide range of sound frequencies or waves comprising means to transform the waves into electrical oscillations, a plurality of branch circuits leading therefrom, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations andsuppressing other frequencies whereby the initial range of frequencies is separated into a plurality offrequency bands, aibalancedmodulator connected with at least one of the filter means carrying a higher frequency band means producing a carrier frequency and connected with the input side of each balanced modulator for modulating the frequency'band carried thereby into a low frequency and a high frequency side band, filtermeans in the output of each balancedmodulator for passing the low frequency side band and suppressing the high frequency side band, and means for record each low frequency side band and the unm ulated low fre-.

output of each balanced modulator for passing quency into a low frequency side band and each .for'each recording for transforming the same a low frequency and a high frequency side band,

been separated into a plurality of frequency ,quency band and a frequency from which the carrier frequency can be derived,

34. An apparatus for recording awide range of sound frequencies or waves comprising means to ransform the wavesdnto electrical oscillations, a plurality of branch circuits leading therefrom, filtering means in each branch circuit for passing a band of frequencies of the electrical oscillations and suppressing other frequencies whereby th initial range of frequencies is sep- 10 arated into a plurality of frequency bands, a balanced modulator connected with at least oneof the filter means carrying a higher frequency band, means producing a fundamental frequency from which a carrier frequency can be derived l5 and connected with the input side of each balanced modulator for modulating the frequency band carried thereby into a low frequency and a high frequency side band, filter means in the modulated b a carrier frequency into a low frequency side bandwhichrhas been recorded as 5 well as any unmodulated frequency band and a frequency from which the carrier frequency can be derived comprising means for each recording for transforming the same into electrical oscillations, means for producing the carrier frequency from the frequency recording and connected with the output of each of the next aforesaid means which carries a side band frequency for demodulating each side band frequency into a low frequency and a high frequency side band, means for passing the high frequency side band and suppressing the low frequency side band and the carrier frequency whereb the initial frequency band is recreated, the output of each of the next aforesaid means and any transforming means carrying an unmodulated frequency band being connected whereby the reconverted frequency band or hands are mixed with each other and with any unmodulated frequency band or hands to restore the initial frequency range.

38. An apparatus for reproducing a wide range of electrical frequencies or oscillations which have been separated into a plurality of frequency bands and at least one frequency band being modulated into a low frequency side band which has been recorded as well as any unmodulated frequency band comprising means for each recording for transforming the same into electrical oscillations, a balanced demodulator connected with each of the aforesaid means which carries a the low frequencyside band and suppressing the high frequency side band, and means for recording each low-frequency side band and the unmodulated low frequency band and the fundamental frequency upon separate sound tracks.

An apparatus for reproducing a wide range of electrical frequencies or oscillations which have been separated into a plurality of frequency bands and at ileast one frequency band having been converted into a low frequency side band 30 and each low requency side band and any unmodulated frequency band being recorded comprising means for'each recording for transforniof the aforesaid means which carries a side band frequency for demodulating the same into a low frequency and a high frequency side band, means for passing the high frequency side band and suppressing the low frequency side band and the 40 carrier, frequency wherebythe initial frequency band is recreated, the output of each of the next. aforesaid means and the transforming means for any unmodulated frequency band being connected whereby the demodulated frequency band or bands are mixed with each other and with any unmodulated frequency band or bands to restore the initial frequency range.

' 36. An apparatus for reproducing a wide range of electrical frequencies or oscillations which have been separated into a plurality of frequency bands ing means connected balanced demodulator with the input side of each for. demodulating each side band frequency into a low frequency and a high frequency side band, filter means for passing the high frequency side band and-suppressing the low frequency side band whereby the initial frequency band is recreated, and the output of each of the next aforesaid means and the output of all transforming means carrying an unmodulated frequency band being connected whereby the demodulated frequency band or bands are mixed with each other and quency band or bands to restore the initial fre quency range. 39. An apparatus for reproducing a wide range of sound frequencies or waves which have been separated into a plurality of frequency bands and recordings upon separate sound tracks having been made of at least, one high frequency band modulated into a low frequency side band and an unmodulated low frequency "bandcomprising means for each sound track for transforming the same into electrical oscillations, carrier frequency producing means connected with the output side of the transforming means which carries a side band frequency for demodulating the same into a low frequency and a high frequency side band,

low frequency side band and any unmodulated frequency band being recorded comprising means into electrical oscillations, a carrier frequency of the same frequency as the modulating frequency and being connected with each of the aforesaid means which carries a side band frequency for demodulating the same into means for producing and suppressing the carrier frequency and low frequency side band whereby the initial frequency-band or bands is recreated, the output of each of the next the carrier frequency whereby the initial fre quency band is recreated; the'output of each of the next aforesaid means and thetransforming means for any unmodulated frequency band being connected whereby the' demodulated frequency band or bands are mixed with each other and with any-unmodulated frequency band or bands to restore theinitial frequency range.

37. An apparatus for reproducing a wide range 1 of electrical frequencies or oscillations which have 7 quency band being connected whereby the de-' modulated frequency band or bands are mixed with each other quency band to restore thejinitial frequency 'range,'and nice to reproduce the initial frequency range as sound waves.

bands. and at least one frequency band being side band frequency, carrier frequency produowith any unmodulated 'fremeans for passing the high frequency side band aforesaid means and ofthe transforming means for theunmodulated freand with the unmodulated fre-l 40. An apparatus for reproducing a wide range of sound frequencies or waves which have been separated into a plurality of frequency bands and recordings upon separate sound tracks having been made of at least one high frequency band modulated by a carrier frequency into a low frequency side band and an unmodulated frequency band and a frequency from which the carrier frequency can be derived comprising means for each sound track for transforming the same into electrical oscillations, means for producing a carrier frequency from the frequency sound track'and connected with the output side of at least one of the next: aforesaid means which carries a low frequency side band for demodulating the same into 'a low frequency and a high frequency side band, means for passing the, high frequency side band and suppressing the carrier frequency and the low frequency side hand whereby the initial frequency band is re-,

created, the output of each of the next aforesaid means and the transforming means carrying the unmodulated frequency band being connected whereby the demodulated frequency band or-bands are mixed with each other and with the unmodulated frequency band to restore the initial frequency range. I

41. An apparatus forreproducing a wide range of sound frequencies or waves which have been separated into a plurality of frequency bands quency intoa low frequency and a high. fre-' quency side band, filter. means for passing the high frequency side'band and suppressing the low frequency sideband whereby the initial frequency band is recreated, the output of each of ing connected whereby the demodulated frequency band or hands are mixed with each other andwith the unmodulated frequency band to restore the initial frequency range, and means to reproduce the initial frequency range as sound waves.

I 42. An apparatus for reproducing a wide range of sound frequencies or waves which have been separatedinto plurality of frequency bands and recordings upon separate sound tracks having been made of at least one of the higher frequency bands modulated by acarrier frequency into a low frequency side band-and an unmodulated low frequency band and the fundamental frequency comprising means for each sound track for transforming the same into electrical oscillations, a balanced'gdemodulator connected with each of the next aforesaid means which carries a 'side band frequency, means for creating a carrier frequency from the reproduced fundamental frequency and connected with the input side of each demodulator for demodulating each side hand frequency into a low frequency and a high frequency side band, filter means for passing the high frequency side band and suppressing the low frequency side band whereby the initial frequency band is recreated, the output of eachof the next aforesaid means and the transforming means for the unmodulatedfrequency band being connected whereby the demodulated frequency band or bands'are mixed with each other and with the unrnoclul'ated frequency band to restore the initial frequency range, and means to reproduce the initial frequency range as '35- sound waves. V

43. A recording for reproducing a wide range of frequencies with high fidelity comprising a track recording a low frequency. band of the range of frequencies to be recorded, and at least one other track recording the low frequency side band of a modulated high frequency band.

the next aforesaid means and the transforming means for the unmodulated frequency band be- 44. A recording for, reproducing a wide range of frequencies with high fidelity comprising a track recording a low'frequency side band of the range of frequencies to .be recorded, and a track recording a frequency from which acar-. rier frequency can be derived for demodulating the side band frequencyi V W. ROBERTS. 

